JP5643091B2 - Method for preparing modified metal oxide nanoparticle dispersion - Google Patents

Description

  The present invention relates to a polymer composition comprising modified nanoparticles dispersed in a polymer and a method for its preparation.

  In a wide variety of applications including optical devices such as lenses, polymer compositions are used in place of glass compositions. The specific requirements imposed on the application determine the type of polymer chosen. For example, for certain applications, it is desirable to provide a polymer composition having improved physical properties such as mechanical strength, heat resistance, or toughness. Furthermore, processability, formability and cost also need to be considered.

  In the case of optical devices, improved optical properties such as refractive index, transparency or transparency, and optical uniformity can also be important, and polymer compositions with these improved properties Has also been prepared. For example, U.S. Pat. No. 4,990,653 discloses a sulfur-containing oligomer composition that can be polymerized to form a cured product having a refractive index of 1.60 or higher with excellent transparency and optical uniformity. The preparation is described. In addition, US Pat. No. 5,683,628 describes photochromic resin compositions comprising a specific class of di (meth) acrylate compounds. According to the description, such a compound has excellent heat resistance, mechanical strength, adhesiveness, moldability and light resistance. These materials can be used as an antireflection film in a lens, for example. The refractive index of the composition can be controlled by varying the amount of the particular di (meth) acrylate compound and can be 1.54 or higher. However, the ever increasing demand for improved optical performance, along with the need for improved physical properties, processability and reduced cost, has limited the use of these types of custom polymers. Has reached the point.

  Some types of metal oxides are known to have a high refractive index. For example, typically titanium dioxide (titania), zirconium oxide (zirconia), cerium oxide (ceria), tantalum oxide, niobium oxide, zinc oxide, barium titanate and strontium titanate are about 1.7 or more (about A refractive index greater than or equal to 1.7). However, these metal oxides can be difficult to disperse well in polymer systems, and poor dispersibility is generally poor optical properties. Modified metal oxides have been prepared to provide improved dispersibility in various matrices including solvents and polymer systems, and the type of modification used depends on the particular system. . For example, in order to prepare modified silica particles for use in tire applications, silane coupling agents having functional groups capable of reacting with silica and a rubber matrix are used. Modifications to other metal oxides are also known, including those with a high refractive index. However, when modifying metal oxides, there is a concern that the refractive index of the material will be significantly reduced, thereby causing a decrease in the effectiveness of the modified metal oxide for optical applications. The Furthermore, modification of metal oxide nanoparticle dispersions (with particle sizes of less than 50 nm) often results in an undesirable increase in particle size and subsequent loss of optical clarity. Can occur. To maintain particle size, generally use stabilizers such as dispersants, which often have a negative impact on physical and optical properties, or mechanical techniques for particle size reduction It is necessary to use For example, US Patent Application Publication No. 2007/0036962 describes a method for preparing a nanoparticle-resin composite. This preparation method includes a step of modifying a metal oxide dispersion with an organic compound. The resulting modified metal particles are then isolated by precipitation and reagglomeration and subsequently dispersed in the polymer using mechanical dispersion techniques. Such multi-stage processes are often cumbersome and inefficient, costly, and require considerable labor. In addition, the resulting composite material may have undesired optical properties including haze and high scattering.

  Accordingly, a polymer composition for an optical device, which can exhibit overall good performance, including mechanical properties and processability, with improved optical properties, particularly high refractive index and transparency. There is a need in the industry to provide goods. Furthermore, there is a need for a method of preparing a polymer composition containing a metal oxide nanoparticle dispersion without impairing the size of the metal oxide nanoparticles.

The present invention relates to a method for preparing a polymer composition comprising modified nanoparticles dispersed in a polymer. In one embodiment, the preparation method comprises the following steps:
i) combining a metal oxide nanoparticle dispersion in a non-aqueous solvent and at least one coupling agent to form a modified metal oxide nanoparticle dispersion in a non-aqueous solvent;
ii) combining the modified metal oxide nanoparticle dispersion with at least one polymer in a non-aqueous solvent; and
iii) removing the non-aqueous solvent to form a polymer composition;
Is included. In a second embodiment, the preparation method comprises the following steps:
i) combining a metal oxide nanoparticle dispersion in a non-aqueous solvent and at least one coupling agent to form a modified metal oxide nanoparticle dispersion in a non-aqueous solvent;
ii) combining the modified metal oxide nanoparticle dispersion with at least one monomer in a non-aqueous solvent to form a polymerizable composition;
iii) removing the non-aqueous solvent; and
iv) polymerizing the polymerizable composition to form a polymer composition;
Is included. In both of the above embodiments, the coupling agent has a refractive index of 1.48 or more. Alternatively or additionally, the polymer composition has a refractive index greater than or equal to 1.5. Preferably, the polymer composition is transparent. The present invention further relates to a polymer composition comprising modified nanoparticles dispersed in a polymer prepared by the methods described herein.

  Both the foregoing general description and the following detailed description are exemplary only for purposes of illustration, and from that description further description of the invention as set forth in the claims may be made. It should be understood that it is intended to be done.

Representative coupling agents that can be used in the compositions and methods of the present invention are shown. It is the graph which showed the light absorbency of the polymer composition of this invention in a certain wavelength range. It is the graph which showed the light absorbency of the polymer composition of this invention in a certain wavelength range. 2 is a graph showing the transmittance (%) of a polymer composition of the present invention in a wavelength range after exposure to UV light at various time intervals. 2 is a graph showing the transmittance (%) of a polymer composition of the present invention in a wavelength range after exposure to UV light at various time intervals. It is the graph which showed the transmittance | permeability (%) of the polymer composition of this invention in various wavelengths when heat aging was performed in a different period.

  The present invention relates to a method for preparing a polymer composition comprising a modified nanoparticulate metal oxide in a polymer, and a polymer composition prepared by such a method.

  The method of the present invention combines a metal oxide nanoparticle dispersion in a non-aqueous solvent and at least one coupling agent to form a modified metal oxide nanoparticle dispersion in a non-aqueous solvent. The process of carrying out is included.

  The metal oxide may be any inorganic oxide known in the art. For example, the metal oxide may be titanium dioxide (titania), zirconium oxide (zirconia), cerium oxide (ceria), zinc oxide, barium titanate or strontium titanate. Preferably, the metal oxide is barium titanate. The metal oxide has a very small average particle size when dispersed in a non-aqueous solvent, as described in more detail below, and therefore forms a nanoparticle dispersion in the non-aqueous solvent. . Here, the “nanoparticle dispersion liquid” means that the average particle diameter of dispersed particles (in this case, metal oxide) is less than 50 nm. For example, the metal oxide in the non-aqueous dispersion preferably has a particle size of less than 50 nm, more preferably about 2 to about 15 nm, or more preferably less than 20 nm, including about 5 to 10 nm. ing. The metal oxide in the dispersion preferably has a particle size of 0.5 nm or more, more preferably 1 nm or more. The particle size can be measured using any technique known in the art including, for example, dynamic light scattering or small angle X-ray scattering (SAXS). Further, preferably, the metal oxide has a refractive index of about 1.8 or greater, such as about 1.9 to 2.9. Refractive index values are for room temperature and sodium D line (589 nm) when used herein, unless otherwise noted.

  The non-aqueous solvent is a solvent or a mixture of solvents, such solvents including 10% or less water, preferably 2% or less water or 1% or less water (trace level). Contains up to weight percent water. Furthermore, the non-aqueous solvent is such that the metal oxide forms a stable nanoparticle dispersion (having a particle size of less than 50 nm at a concentration of about 0.001% to about 10% by volume). Non-aqueous solvents may include various solvents that are immiscible with water, such as hydrocarbon solvents, ester solvents (including ethyl acetate), and aromatic solvents (including toluene, xylene, benzene, etc.). Also, as will be described in detail below, other non-hydratable solvents can be selected depending on the solubility characteristics and reactivity of the coupling agent, polymer or monomer. Preferably, the solvent is soluble in water or otherwise miscible with water and may therefore contain trace amounts of water. Examples include hydratable ethers (eg tetrahydrofuran), ketones (eg methyl ethyl ketone or acetone), glymes (eg diglyme) and glycol ethers (eg ethoxyethanol or ethoxypropanol). . Furthermore, the non-aqueous solvent may be a monomer used to form the polymer composition, or it may include monomers described in more detail below.

Metal oxide nanoparticle dispersions in non-aqueous solvents can be prepared using any method known in the art. Such methods are described, for example, in the following references which are each incorporated herein by reference: G. Hsiue, Li W. Chu, and IN Lin, Colloids and Surfaces A : Physiochm. Eng. Aspects, 294, (2007), 212-220; U. Paik, V. Hackley, S. Choi, and Y. Jung, Colloids and Surfaces A: Physiochm. Eng. Aspects, 135, (1998) , 77-88, K. Sumida, K. Hiramatsu, W. Sakamoto, and T. Yogo, Journal of Nanoparticle Research , (2007), 9 (2), 225-232, and T. Yogo, R. Fukuzawa, W Sakamoto, and S. Hirano, Journal of Nanoparticle Research , (2005), 7, 633-640. For example, a metal oxide may be formed in a non-aqueous solvent by hydrolyzing the metal oxide precursor. Alternatively, the metal oxide may be formed and dispersed in a non-aqueous solvent under high shear conditions to form a nanoparticle dispersion. The metal oxide may be formed by decomposing a precursor of the metal oxide. It is preferred not to use a dispersant.

In the method of the present invention, the modified metal oxide nanoparticle dispersion is formed by combining the metal oxide nanoparticle dispersion with a coupling agent. The coupling agent can be any material that can react with or interact with the metal oxide. For example, the coupling agent may comprise at least one group capable of reacting with the metal oxide, for example by forming a covalent or ionic bond with the surface of the metal oxide. Examples of reactive groups include metal-containing groups such as Si-, Ti-, Sn- or Se-containing groups, carboxylic acid groups such as aryl or alkyl carboxylic acids, sulfinic acid or sulfonic acid groups, thiol, and phosphorus-containing groups. For example, a group having at least one P—O or P═O bond (phosphonic acid group, phosphinic acid group, phosphinic acid group, phosphorous acid group, or phosphate group, diphosphate group, triphosphate group or pyrophosphate group As well as its partial esters or salts thereof. For example, the reactive group may be a phosphonic acid group, a partial ester thereof, or a salt thereof. Here, “partial ester thereof” means a partial phosphonic acid having a phosphonic acid group having the formula: —PO ₃ RH (wherein R is an aryl group, an alkaryl group, an aralkyl group or an alkyl group). It means that it may be an ester group or a salt thereof. “Salt thereof” means that the phosphonic acid group may be in a partially or fully ionized form with a cationic counterion. Thus, the reactive group of the ^{_{formula: -PO 3 H 2, -PO 3}} H - M + may include a group having a (monobasic salt), or _-PO ³ -2 ^{M +2} (dibasic salt). In the above formula, M ⁺ is a cation such as Na ⁺ , K ⁺ , Li ⁺ or NR ₄ ⁺ , and R may be the same or different, and may be hydrogen or, for example, substituted or unsubstituted aryl. Represents an organic group such as a group and / or an alkyl group.

Also, the coupling agent can react with the medium in which it is dispersed or can react with each other. Thus, the coupling agent “couples” to the metal oxide and the medium to form a modified metal oxide nanoparticle dispersion. For example, the coupling agent further comprises at least one group capable of reacting with a non-aqueous solvent, together with a group capable of reacting with or reacting with a metal oxide. In this example, the coupling agent, at least one polyalkylene oxide group, for example the following group of the formula _{:-( O-ALK1) x - (} O-ALK2) y - (O-ALK3) z - may contain. In the above formula, ALK1, ALK2 and ALK3 are linear or branched C1-C8 alkylene groups, x is 1-10, and y and z are 0-10. It has been found that using such a coupling agent, a modified metal oxide nanoparticle dispersion in a non-aqueous solvent such as an ether solvent can be used, for example, in the same non-aqueous solvent, for example. It can be prepared from a nanoparticle dispersion of a metal oxide such as titania or barium titanate. As another example, the coupling agent may include at least one siloxane group having the following formula: R ₁ — [SiR ₂ R ₃ —O] _n —, wherein R ₁ is C 1- A C8 alkyl group (for example, a methyl group, an ethyl group, a propyl group, or a butyl group), and R ₂ and R ₃ are independently a C1-C6 alkyl group or an aryl group (for example, a methyl group or a phenyl group). Yes, and n is 1-12, including 1-9. In this example, the siloxane group of the coupling agent has the following formula: R ₁ — [SiMe ₂ —O] _n —SiMe ₂ — (ALK ₁ —O) _x — ( _where ALK ₁ and x are as described above. It may be a group having Selection of reactive groups and ALK1, ALK2, ALK3, R ₁ , R ₂ , R ₃ , n, x, y, and z depends on the type of metal oxide and non-aqueous medium in which the nanoparticulate metal oxide is dispersed Will depend on the type of For example, in the case of a coupling agent comprising at least one polyalkylene oxide group having the above formula, x in the formula can be 2-8 and y and z can be 0. Such groups will be polyalkylene oxide groups such as polyethylene oxide, polypropylene oxide or polybutylene oxide. In this example, the coupling agent has the _{formula: (HO) 2 P (O} ) - (O-ALK1) x or _{(HO) 2 P (O)} - (ALK1-O) to include groups having _x Can do.

  The coupling agent may further be capable of reacting or interacting with the polymerizable monomers described in more detail below and the polymers formed from the polymerizable monomers, or both. For example, if the monomer is a radically polymerizable monomer, the coupling agent may also have at least one radically polymerizable group such as an acrylate group or a methacrylate group. The coupling agent may also be capable of reacting or interacting with the polymer of the polymer composition described in more detail below. For example, if the polymer is an ether polymer such as a polyalkylene oxide or a siloxane polymer such as a silicone oil, the coupling agent can be derived from a modified metal oxide such as that of the polyalkylene oxide coupling agent described above. Such a group may be included to make it possible to form a nanoparticle dispersion in the polymer.

  The coupling agent may be in liquid or solid form. For example, the coupling agent can be either a dispersion or a solution in a non-aqueous solvent. The non-aqueous solvent should not be reactive with the coupling agent.

  Coupling agents having a high refractive index are particularly useful with respect to polymer compositions formed by the method of the present invention. Preferably, the coupling agent has a refractive index of 1.48 or higher, more preferably 1.5 or higher, even more preferably 1.55 or higher, and most preferably 1.6 or higher, such as 1.64 or higher. ing. Unlike conventional coupling agents, coupling agents having these refractive index values, in combination with metal oxides, have improved overall performance, especially optical performance, in polymer compositions. A modified metal oxide having can be formed. Examples of coupling agents having such refractive index values include those comprising at least one arylene or heteroarylene and at least one sulfur-containing group, such as either a thioether group or a sulfone group, or at least one halogen. . Particular examples include the compounds shown in FIG. For comparison purposes, conventional coupling agents and their corresponding refractive index values (RI) are shown in Table 1 below.

  In the method of the present invention, a metal oxide nanoparticle dispersion in a non-aqueous solvent and a coupling agent are combined to form a modified metal oxide dispersion also called a nanoparticle dispersion in a non-aqueous solvent. Form. The modified metal oxide thus contains the reaction product of the metal oxide and the coupling agent. The amount of metal oxide and coupling agent combined to form the modified metal oxide is, for example, the type of metal oxide (eg, particle size, surface area, density and number and type of reactive groups) and modification Variations can be made according to various factors, including the properties desired for the metal oxides formed. For example, the metal oxide and the coupling agent have a weight ratio of metal oxide to coupling agent (metal oxide: coupling agent) of about 4: 1 to about 100: 1, about 25: 1 to about 100: 1, and from about 50: 1 to about 100: 1 may be used as a range of about 1: 4 to 100: 1. In general, the higher the density of the metal oxide, the smaller the ratio (weight) of the metal oxide to the coupling agent. The smaller the particle size, the greater the surface area (by weight), which means that the ratio of metal oxide to coupling agent is smaller. It would also be desirable to have a higher ratio of high metal oxide to coupling agent depending on the refractive index of the coupling agent in order to minimize the refractive index of the final polymer composition ( This ratio can be made smaller for coupling agents with a high refractive index). In the case of the process according to the invention, the amount of coupling agent used can be controlled so that the potential required during purification due to an excess of coupling agent is avoided. In addition, in this way, the presence of a significantly excessive amount of a low refractive index coupling agent does not adversely affect the composition, so a refractive index lower than that of the polymer is reduced. When the coupling agent has, it provides a polymer composition having a higher refractive index.

  Unexpectedly, the resulting modified metal oxide was also found to be in the form of a nanoparticle dispersion. Thus, it has been found that a modified metal oxide can be prepared from a metal oxide nanoparticle dispersion in a non-aqueous solvent without significantly impairing the properties of the nanoparticles.

  In the first embodiment of the method of the present invention, the method further comprises combining the nanoparticle dispersion of the modified metal oxide and the polymer in a non-aqueous solvent. The polymer can be in liquid or solid form, and a wide variety of different polymers may be used depending on the properties desired for the polymer composition and its use. For example, the type of polymer can be a silicone polymer, such as a polysiloxane homopolymer or copolymer (including, for example, methylphenyl polysiloxane, methylphenylhydrogen polysiloxane, diphenylpolysiloxane, diphenylhydrogen polysiloxane, or mixtures thereof), epoxy, Includes polycarbonate, polyester and polyurethane. Suitable silicone polymers are described in U.S. Patent Application Publication Nos. 2007/0036962 and U.S. Pat. Nos. 7,160,972 and 6,160,151, which are incorporated herein by reference. It includes what is. Preferably, such polymers are soluble in non-aqueous solvents and are used as either dispersions or solutions in non-aqueous solvents. Further, such a polymer may be a dispersion or solution in an organic solvent different from the non-aqueous solvent, in which case a polymer solution soluble in the non-aqueous solvent is formed.

  In the case of this embodiment, the method of the present invention comprises the step of combining the modified metal oxide nanoparticle dispersion and the polymer, and then removing the non-aqueous solvent to form a modified metal oxide dispersion in the polymer. In addition. A wide variety of different methods known in the art may be used to remove the non-aqueous solvent. For example, the non-aqueous solvent may be removed by evaporation at either atmospheric pressure or reduced pressure. Preferably, the non-aqueous solvent can be removed under conditions that do not cause significant discoloration or degradation of the polymer. In addition, for this reason, a part of the non-aqueous solvent may be removed before combining the modified metal oxide nanoparticle dispersion and the polymer. , The amount of non-aqueous solvent removed after combining the dispersion and polymer can be minimized and, for example, the thermal history in the polymer can be reduced. Although some of the solvent may be removed, the modified metal oxide should still be in the form of a dispersion (ie, some but not all of the non-aqueous solvent can be removed). ). The method may also use solvent exchange, particularly to replace non-aqueous solvents with those that can be more easily removed or more economical.

  In the second aspect, the method of the present invention further comprises a step of forming a polymerizable composition (polymerizable composition) by combining the modified metal oxide nanoparticle dispersion in a non-aqueous solvent and the monomer. It is out. Monomers can be inorganic or organic compounds capable of forming polymers under conditions known in the art. For example, the monomer can be any radically polymerizable monomer, including, for example, an ethylenically unsaturated monomer, such as a substituted or unsubstituted alkyl acrylate or methacrylate monomer, or a substituted or unsubstituted styrenic monomer. Other monomers will be familiar to those skilled in the art.

The monomer may be capable of forming a homopolymer or copolymer having a high refractive index of, for example, 1.5 or higher. As an example, the following formula: CH ₂ ═C (R ¹ ) —COOR ² , wherein R ¹ is hydrogen or a methyl group, and R ² is a substituted or unsubstituted phenyl, benzyl or 2-phenoxyethyl group. Mono (meth) acrylate compounds having a certain). Specific examples of mono (meth) acrylate compounds include phenyl (meth) acrylate, benzyl (meth) acrylate, 2-phenoxyethyl (meth) acrylate, 1,3,5-tribromophenyl (meth) acrylate, and 2 Mention may be made of-(1 ', 3', 5'-tribromophenyl) -oxyethyl (meth) acrylate. Examples of the monomer include 2,2′-bis [4- (methylacryloyloxyethoxy) phenyl] propane and 2,2′-bis [(3,5-dibromo-4-methacryloyloxyethoxy) phenyl] propane. Di (meth) acrylate including Further examples include various sulfur-containing diacrylate or dimethacrylate compounds, such as the formula: (CH ₂ ═C (R ¹ ) —COOR ³ —S—R ⁴ ) ₂ —Ar, where R ¹ is hydrogen Or a methyl group, R ³ and R ⁴ are, independently of each other, a C1-C12 alkylene group, and Ar is a substituted or unsubstituted arylene or heteroarylene group such as a substituted or unsubstituted phenylene. A group having a group). Examples include those described in US Pat. Nos. 4,990,653 and 5,683,628.

  The monomer may be a mixture of polymerizable compounds. For example, such a monomer may be a mixture comprising any of the specific monomers as described above, together with at least one monomer that imparts additional optical or physical properties to the polymer composition obtained after polymerization. It's okay. For example, such monomers include at least one mono (meth) acrylate compound such as methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) Acrylate, isobutyl (meth) acrylate and t-butyl (meth) acrylate, cyclopentyl (meth) acrylate, cyclohexyl (meth) acrylate, methylcyclohexyl (meth) acrylate, trimethylcyclohexyl (meth) acrylate norbornyl (meth) acrylate, isobornyl (Meth) acrylate, adamantyl (meth) acrylate, dicyclopentanyl (meth) acrylate and dicyclopentenyl (meth) acrylate may be included. Further, it may contain a di (meth) acrylate compound and other crosslinkable monomers. Further, such monomers may be polymerizable oligomeric compounds and / or small molecular weight polymers (often referred to as prepolymers) that can be further polymerized.

  In this embodiment, the method of the present invention further includes a step of removing the non-aqueous solvent and polymerizing the polymerizable composition. These steps may be performed in any order. A wide variety of different methods known in the art may be used to remove the non-aqueous solvent. For example, as described above with respect to the first embodiment, the non-aqueous solvent may be removed by evaporation at either atmospheric pressure or reduced pressure. Thus, in this embodiment, the non-aqueous solvent should have a boiling point below that of the monomer. The non-aqueous solvent can be removed under conditions that do not cause polymerization of the monomer. According to another method, the polymerization may be performed simultaneously with the removal of the solvent.

  In addition, it is known in the art to polymerize the monomers of the polymerizable composition, including, for example, radical polymerization (eg, with or without the use of a catalyst, such as hydrosilation) or condensation polymerization. Any method may be used and the particular method will depend on the type of monomer. For example, in the case of so-called two-component silicones, a modified metal oxide nanoparticle dispersion in a non-aqueous solvent and vinyl siloxane may be combined with a catalyst to form the first component, and the vinyl siloxane and siloxane comonomer The first component may be polymerized by combining with a second component containing. Polymerization is caused by the reaction of the catalyst and siloxane comonomer with vinyl siloxane. The surprising advantage of the method of the present invention in such a polymerization system is that the ratio of siloxane comonomer and vinyl siloxane due to the small amount of catalyst required and / or the presence of the modified metal oxide nanoparticle dispersion. Can be modified, and can lead to additional cross-linking possibilities due to the interaction / reaction of the siloxane compound with the coupling agent and / or metal oxide surface.

  In both embodiments, the monomer or polymer may be present in any amount, depending on various factors including the desired properties and use of the polymer composition. For example, when preparing polymer compositions useful in optical devices where improved optical properties such as high refractive index are desired, monomers or polymers having a refractive index lower than that of the modified metal oxide Is selected, the amount of monomer or polymer should be minimal to provide a polymer composition with a high refractive index. In general, the higher the refractive index of the monomer or polymer, the greater the amount of monomer or polymer that may be used. Furthermore, the higher the refractive index of the modified metal oxide or the refractive index of the metal oxide and / or coupling agent containing the modified metal oxide, the more monomer or polymer that may be used. A large amount (i.e., a high refractive index modified metal oxide is not so much needed to still produce a polymer composition with a high refractive index), and this also means, for example, improved mechanical and This is desirable in providing rheological properties and reduced costs. Generally, the amount of monomer or polymer can range from about 5 to 95% by weight, based on the total weight of the polymer composition. For example, the monomer is present in an amount of about 5-90% by weight, including an amount of about 5-70% by weight and an amount of about 5-50% by weight, based on the total weight of the polymer composition. Good.

  For this purpose, the method of the present invention comprises the following steps: combining a metal oxide nanoparticle dispersion in a nonaqueous solvent and a coupling agent to form a modified metal oxide nanoparticle dispersion in a nonaqueous solvent. This nanoparticle dispersion is combined with the polymer and subsequently the non-aqueous solvent is removed, or the nanoparticle dispersion is combined with the monomer and the non-aqueous solvent is subsequently removed. Forming a polymer composition comprising the modified metal oxide dispersed in the polymer by any order of polymerizing the monomers to form the polymer. Unexpectedly, it has been found that the nanoparticle properties of the metal oxide are maintained throughout each step of the method. Therefore, in the method of the present invention, a polymer composition containing modified nanoparticles dispersed in a polymer can be produced from a metal oxide nanoparticle dispersion in a non-aqueous solvent. It is not necessary and the particle size does not increase significantly. Furthermore, it has been found that once a metal oxide nanoparticle dispersion is formed, no additional dispersion or particle size reduction steps are required, such as the use of a mechanical dispersion device. In fact, the method of the present invention does not involve the isolation or purification of intermediate modified metal oxides and is therefore considered to be a single pot process for preparing polymer compositions containing nanoparticulate metal oxides. Can do. According to this method, it is possible to prepare a polymer composition having a uniform nanoparticle dispersion throughout, and it is possible to prevent loss of transmittance due to scattering without significant aggregation of particles. It is important.

  The invention further relates to a polymer composition comprising nanoparticles dispersed in a polymer, preferably modified nanoparticles, such as modified nanoparticle metal oxides, produced by the method described above. The modified nanoparticles include about 10 to about 95% by weight, about 30 to about 95% by weight, or about 50 to about 95% by weight, based on the weight of the polymer composition. It may be present in an amount of 5 to about 95% by weight. Further, the modified nanoparticles can comprise about 5 to about 90% of the polymer composition, including amounts of about 20 to about 90%, about 30 to about 90%, or about 15 to about 50% by volume of the polymer composition. It may be present in an amount of volume%.

  In one embodiment, the polymer composition of the present invention has a refractive index of 1.5 or greater. More preferably, the refractive index of the polymer composition is 1.6 or more, more preferably 1.7 or more, and most preferably 1.8 or more. Also, the polymer composition is preferably transparent rather than opaque, turbid or translucent. As used herein, a transparent material is one that allows a high level of light transmission (i.e., low absorbance) for the visible region (400-800 nm). The absorbance (A) of a material having a sample thickness L (path length measured in cm) and modified metal oxide concentration c (weight of modified metal oxide / weight of composition) is given by the following formula (I): And can be determined by measuring the transmittance (% T) at a particular wavelength.

  The transparent composition of the present invention preferably has i) an absorbance (A) of 400 nm, ≦ 6, preferably ≦ 5, more preferably ≦ 4, most preferably ≦ 3.5, ii) 450 nm, ≦ 3, preferably ≦ 2.5, more preferably ≦ 2 absorbance (A), and iii) have an absorbance (A) at 650 nm of ≦ 1, preferably ≦ 0.5, more preferably ≦ 0.34. doing. Unexpectedly, it has been found that polymer compositions with high refractive index values can be produced from compositions comprising at least one modified metal oxide, and such compositions Can be transparent and can have a low absorbance (high transparency) across a wide range of wavelengths, particularly the blue region.

  Therefore, in this embodiment, the polymer composition of the present invention is transparent and has a light color. The degree of color (level) will depend on various factors including, for example, the type and size of the modified metal oxide, the type of polymer and the relative amounts of each, and the thickness of the sample. For example, a polymer composition having a thickness of about 200 microns prepared by combining a nanoparticle dispersion of a modified metal oxide (eg, barium titanate) and a polymer (eg, silicone) is transparent while It was found that the color changes between light yellow and amber depending on the amount of the modified metal oxide. However, what has proved unexpected is that the degree of color may be further reduced by irradiating the composition with UV light. Photobleaching (photobleaching) or photoaging (photoaging) of the composition can be performed under a wide variety of conditions including, for example, irradiation with UV light for several hours at room temperature. Accordingly, the method of the present invention may further include the step of photoaging the polymer composition to reduce the degree of color.

  In another embodiment, the polymer composition of the present invention is transparent and remains transparent after thermal aging. For example, in certain applications, it is desirable that the polymer composition withstand high temperature and high humidity conditions for an extended period of time, such as 1000 hours or more, and remain transparent without significant color change. . Unexpectedly, the polymer composition of the present invention prepared by the above method can withstand high temperature conditions over a long period of time and, therefore, thermally resistant optical properties. It was found to have

  Although the polymer composition of the present invention can be used in a variety of different applications, it has been found that it is particularly useful where a high refractive index is desired. For example, it may be used in various types of optical devices including, for example, lenses, prisms, light emitting diodes, holographic data storage devices, photonic crystal devices, optical waveguides, reflectors, immersion materials and the like. Accordingly, the present invention further relates to an optical device comprising any of the polymer compositions described above.

  Subsequently, the present invention will be further described with reference to the following examples. These examples are intended to illustrate only one example of the present invention.

Example 1
This example describes using the method of the present invention to prepare a polymer composition comprising a nanoparticulate metal oxide and a polymer.

According to the method described in T. Yogo, R. Fukuzawa, W. Sakamoto, and S. Hirano, Journal of Nanoparticle Research , (2005), 7, 633-640, a nanoparticle dispersion of BaTiO _{3 in} glycol ether was prepared. Prepared. However, in the case of this example, instead of the modified composite alkoxide used by Yogo et al. In the hydrolysis, a mixed metal oxide precursor (double metal alkoxide in which DBAT150, Ba and Ti are in a 1: 1 metal ratio, experience The formula: BaTi (OR) _x , available from Gelest, Inc.) was used. Moreover, methoxypropanol was used as a glycol ether solvent. The particle size of the metal oxide in the dispersion was <50 nm at a concentration of 0.23% by weight and this dispersion was found to be stable for several weeks at room temperature.

To this dispersion was added a 10 wt% solution of Ethfac 161 (phosphate ester of 6-ethoxylated decanol, available from Ethox Chemicals) in the same glycol ether solvent (20 wt% based on the weight of the metal oxide). Coupling agent). A dispersion of a modified metal oxide containing a reaction product of BaTiO ₃ and an alkyl phosphate ester was produced. There was no visible scattering and therefore there was no significant increase in particle size.

  PMM0021 (methylphenyl polysiloxane available from Gelest) soluble in a glycol ether solvent was added to the modified metal oxide nanoparticle dispersion. Subsequently, when the solvent was removed by performing vacuum distillation at 50 to 75 ° C., a polymer composition containing a modified metal oxide was formed. There was no visible scattering observed in the resulting polymer composition, and therefore there was no significant increase in particle size. The refractive index of this composition was 1.64.

  The polymer composition of the present invention was sandwiched between two standard incidence glass slides and UV-Vis transmission was measured using a standard laboratory UV-Vis spectrophotometer. Appropriate background was reduced and data was converted to absorbance units using equation (I) above. The results are shown in FIG. 2 (log plot) and FIG. 3 (standard scale). As can be seen from these drawings, the polymer composition of the present invention has low absorbance (low transmittance loss) over a wide wavelength range. Although these compositions were colored slightly yellow, it was further visually observed that they were essentially free of haze.

  It has further been found that the polymer composition of the present invention has improved rheological properties compared to the polymer used to prepare the polymer composition. For example, while phenylmethylpolysiloxane is a low viscosity silicone oil, the polymer composition of the present invention comprising a nanoparticle dispersion of a modified metal oxide in the silicone oil has a significantly increased viscosity. It did not flow at room temperature. Accordingly, it has been found that the polymer composition of the present invention has a combination of good rheological properties and good optical properties.

In addition, several polymer compositions could be prepared using this approach. Here, the coupling agent has a structural formula: Bu— [SiMe ₂ —O] _n —SiMe ₂ — (CH ₂ CH ₂ CH ₂ —O) —CH ₂ CH ₂ OP (O) (OH) ₂ (wherein , n represents a siloxane coupling agent represented by a is 1-9) Buchirupori (dimethylsiloxane), 2-propoxyethyl phosphate or structural formula,: Bu-[SiMe ₂ -O] _n -SiMe ₂ - (CH _{2 CH 2 CH 2 -O) -CH} 2 CH 2 P (O) (OH) 2 ( wherein, n is a siloxane coupling agent represented by a 10) Buchirupori (dimethylsiloxane), 2-propoxy One of the ethyl phosphonic acids.

Example 2
Using the procedure described in Example 1 above, a polymer composition of the present invention comprising 3.9 vol% BaTiO ₃ , 1.9 vol% Ethfac 161 and 95 vol% PMM0021 was prepared. The refractive index of this composition was found to be 1.556. A sample of this composition was placed on the bottom of a glass bottle to form a thin film (film) having a surface area of about 5 cm ² and a thickness of about 150-200 microns as measured by a profilometer. The film was transparent and had a slight yellow color.

  Accelerated UV aging of the above sample was performed by irradiating the sample for several hours in a UV curing chamber (Amergraph V28 VMS) using a 1200 W metal halide lamp (λ = 350-400 nm) under ambient atmosphere. . The polymer composition is sandwiched between two glass slides at normal incidence and the UV-Vis transmission after exposure to UV exposure for 1 and 5 hours using a standard laboratory UV-Vis spectrophotometer. It was measured. The results are shown in FIG. 4 and FIG. 5 (this data is obtained by standardizing FIG. 4 to glass). After only 1 hour (hr) of exposure, no color loss was visible with the naked eye, but UV-Vis transmission data showed that there was a slight color loss. However, after 5 hours of UV exposure, a color drop was clearly visible. This sample was significantly less colored and the transmission (% T) data confirmed this finding. Thus, when the polymer composition of the present invention is exposed to UV light, the color observed can be reduced, and this photobleaching can provide a composition that is not only transparent but also almost colorless. .

Example 3
Using the procedure described in Example 1 above, a polymer composition of the present invention comprising 3.9 vol% BaTiO ₃ , 1.9 vol% Ethfac 161 and 95 vol% PMM0021 was prepared. A sample of this composition was placed on the bottom of a glass bottle to form a thin film having a surface area of about 5 cm ² and a thickness of about 200 microns. The film was transparent and had a slight yellow color.

  Accelerated thermal aging of the thin film was performed by storing the sample in an oven at 150 ° C. for over 1000 hours, and the transmission (% T) for this time was measured at different wavelengths. The results are shown in FIG. As can be seen from the figure, the sample exhibited a slight initial decrease in transmission of several percent after 24 hours in the long wavelength spectrum. However, during the test period (> 1000 hours), this sample was within the experimental error, and the transmittance remained high and relatively constant (transmittance was λ = About 95% at 600-700 nm, 90% at λ = 500 nm, and 75% at λ = 400 nm). Thus, thin films formed from the polymer compositions of the present invention did not exhibit significant “yellowing” (indications of yellowing or a high percentage of near UV light absorption). This is surprising because it was known that oxidation often occurs in these types of systems and that significant yellowing occurs because the oxidation causes degradation. In addition, an uncured silicone sample with the same weight of Ethfac 161 as a control sample showed degradation and severely yellowed within 24 hours at 150 ° C. Thus, the polymer compositions of the present invention have surprisingly been found to be thermally stable and have been found to remain relatively unchanged in optical properties after thermal aging. did.

  The preferred embodiments of the present invention have been described above for the purpose of illustration. The above description is not intended to be exhaustive or to limit the invention to the precise form disclosed. These embodiments were chosen and described in order to explain the main part of the invention and its practical application, and those skilled in the art are suitable in various embodiments and for the specific use envisaged. The present invention can be used with various modifications. It should be understood that the scope of the invention is defined by the claims appended hereto and their equivalents.

Claims (14)

A method for preparing a polymer composition comprising modified nanoparticles dispersed in a polymer comprising the following steps:
i) Hydrolyzing a metal oxide precursor in a non-aqueous solvent to obtain a metal oxide nanoparticle dispersion in a non-aqueous solvent, wherein the average particle size of the nanoparticles is dynamic light scattering or Forming a non-aqueous nanoparticle dispersion that is less than 50 nm as measured using small angle X-ray scattering (SAXS);
and combined ii) a nanoparticle dispersion of a metal oxide of the non-aqueous solvent and at least one coupling agent, the non-aqueous solvent, by forming a nanoparticle dispersion of a modified metal oxide The coupling agent may react with or interact with the metal oxide to form a nanoparticle dispersion, or may react with or interact with the medium in which the coupling agent is dispersed ;
iii) combining the modified metal oxide nanoparticle dispersion with at least one polymer in a non-aqueous solvent; and
iv) removing the non-aqueous solvent to form a polymer composition;
A method for preparing a polymer composition, wherein the coupling agent has a refractive index of 1.48 or more.   The method of claim 1, wherein the coupling agent has a refractive index of 1.6 or greater.   The method of claim 1, wherein the metal oxide and the coupling agent are combined in a weight ratio of metal oxide to coupling agent of 1: 4 to 100: 1.   The method of claim 1, wherein the metal oxide has a refractive index of 1.8 or greater.   The method of claim 1, wherein the metal oxide is titanate.   The method according to claim 1, wherein the metal oxide is rutile-type titania.   The method of claim 1, wherein the metal oxide is barium titanate.   The method according to claim 1, wherein the metal oxide has a particle size of 2 to 15 nm in a nanoparticle dispersion in a non-aqueous solvent.   The method according to claim 1, wherein in the nanoparticle dispersion in a non-aqueous solvent, the modified metal oxide has a particle size of 2 to 15 nm. The coupling agent comprises at least one metal-containing group, at least one carboxylic acid group, at least one sulfinic acid group, at least one sulfonic acid group, at least one thiol group, at least one phosphorus-containing group. Item 2. The method according to Item 1 . The coupling agent includes a group capable of reacting with the polymer, and the group capable of reacting with the polymer is represented by the following formula:
_{- (O-ALK1) x -} (O-ALK2) y - (O-ALK3) z -
Wherein ALK1, ALK2, and ALK3 are linear or branched C1-C8 alkylene groups, x is 1-10, and y and z are 0-10. The method described.   The method of claim 1, wherein the polymer composition has a refractive index of 1.5 or greater.   The method of claim 1, wherein the polymer composition is transparent.   The method of claim 1, wherein the polymer is present in an amount of 5 to 50% by weight, based on the total weight of the polymer composition.

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